Fragments of Union is an intricate, subtle, and compelling study of nearly two centuries of literature, epistemological and political argument, and of the 'grammar of the imagination' that binds and separates these different forms. Susan Manning explores connections 'in' as well as 'between' Scottish and American writing of the eighteenth and nineteenth centuries, gradually and precisely accreting evidence for fundamental and pervasive similarities in the two literatures' structures of thought and of expression. Her thesis is complex, ambitious, and tightly worked; and for readers of Symbiosis, in particular, it will be of pressing interest not only because of its subject matter but also because of its methodology and the reflection it both offers and inspires on the ways in which we find and make connections.

Manning begins her case with a carefully modulated and critically self-observant introduction and with a reading of the early American cartoon in the Pennsylvania Gazette, 'Join, or Die' (1754). Metaphors of connection abound here, as they do throughout the study: Manning describes conjunctions, analogies, associations, resemblance, contiguity, equivalents, affinities, relationships, allusiveness, and conceptual continuities, but does not dwell on the (intriguing) connections between these terms themselves. Instead, she directs us to two larger metaphors - confederation and incorporation – which define the study as a whole. In syntactical terms, confederation is allied to parataxis; politically, to democracy; philosophically, to associationism and to Hume's epistemology of the self; methodologically, to the lists common in the Enlightenment 'Science of Man'; artistically, to Whitman's Leaves of Grass and perhaps to American literature in general. Incorporation, meanwhile - related to hypotaxis, to integrated personal as well as national identity, and to political hierarchy – is to become the more elusive and also the more troubling term as the study develops, and as Scottish and American thinkers ponder the nature of 'union'.

In the course of this opening discussion, Manning remobilises the monolithic 'Enlightenment' reviled by postmodernists and asserts the importance of Enlightenment structures of enquiry and formulation for postmodern thinking, offering a thoughtful critique of Gilles Deleuze's Critique et clinique and its implied 'condition of dissociation'. She also traces the continuity of these structures of thought and rhetoric in Anglo-American philosophical and psychoanalytic theory, examining the ways in which the 'vocabulary' of Hume, Thomas Reid and Dugald Stewart (who coined the term 'transference') informed the work of Freud, William James, and British School developmental psychology. All these links are pertinent and expressive. The reader is just as evocatively introduced to the complexity and nuance of Manning's case, however, by the precision of her disclaimers and discriminations. This is clearly, from the start, an argument steering a controlled course through difficult waters. It sets out to be connective (and to question what that means), but to avoid becoming loosely associative. Manning's command of her materials is magisterial, but her manner recognises temporality and contingency. Just as she refuses to ease Hume's 'seminally modern' Treatise into honorary post-modernity and insists on its connectedness with the politics and rhetoric of its own time, so she emphasises the provenance of her own study in the 'fragmenting union' of modern Britain and in modern performative constructions of 'author' and 'reader' which, she remarks, teach us ‘to be wary, to question our assumptions and our formulations as we make them' (31).

The chapters that follow work around clusters of texts and key metaphors. Beginning with 'The Grammar of the Imagination' and with the pamphlet wars of the years leading up to 1707, Manning identifies the Union foundations of the form and linguistic texture (as well as the propositions) of A Treatise of Human Nature. Imagery of incorporation and ingestion, of secession in perception as well as in politics, pervades and directs Hume's philosophical investigation of connections and of sympathy; and, Manning argues, gives the Treatise a more central place in the cogitations of the eighteenth century than would be suggested by its circulation figures, its own traceable cultural ingestion, alone. To locate the grammar of Hume's influence in this way is both shrewd and sound: it is exciting to trace an 'incorporated' Humean epistemology in an oriental tale by William Duff, the fiction of Henry Mackenzie, and the economic theory of Adam Smith. Manning's next chapter develops the associated metaphors of the debateable land and the boundless appetite, brought together in the image of Holland which, geographically and politically, deconstructs the notion of incorporation even as its comfortable natives eat and drink copiously and childishly. Leisure, luxury, and labour - 'the ambiguity of idleness' (71) – are modulated in a series of readings of the Fable of the Bees, William Byrd II's History of the Dividing Line, James Thomson's Castle of Indolence, George Cheyne's The English Malady (in which, Manning suggests, nervous distempers are associated with the ambitious over-eating which is British imperialism), Adam Smith's Wealth of Nations (more bloated greed and apoplexy), and a range of Walter Scott's novels (here, declining Scott’s own invitations to regard some of his novels as ‘smelling of apoplexy’ and providing instead a sharp and original interpretation of the significance of the 'Dutch' in his work). The metaphors at work in the debatable land of The Betrothed left me wondering about the relationship between this novel (set in the Welsh Marches in the twelfth century) and Peacock's equally neglected novel of four years later, The Misfortunes of Elphin (set in west Wales in the sixth century), which begins with a destructive inundation which has long been read as political metaphor.

Chapter Three, 'Composing a Self', moves from Wilfrid Bion's distinction between 'thoughts' and the process of 'thinking' to explore the 'syntax' of thinking and identity in the private writings of William Byrd II and James Boswell, with excursions into other texts, notably the 'aggregative syntax' of the Commonplace Book of a Pennsylvania Quaker, Milcah Martha Moore's Book, and the absent interiority of Benjamin Franklin's Autobiography. Not surprisingly, perhaps, Boswell runs away with this chapter. Manning gives an authoritative and memorable account of his search throughout his journals ('the first post-Humean account of personal identity', 126) for what she calls a 'composed character', and argues persuasively for the rhetorical and psychological stasis which results from Boswell's compulsively repetitious crises of identity. At some level Boswell has put up a fight, however, for in the conclusion to this chapter Manning emphasises that her aim has been not to 'pathologise' him but 'to identify a particular verbal and grammatical structure uniquely developed in his writing which ... would align Anglo-Scots, American and modern forms of self-expression' (147). Lord Auchinleck père and Boswell's compensatory father-figures claim her attention just as they claim his, with the result that Boswell as 'type' persistently evades incorporation.

In her next chapter Manning turns from attempts at integration to the cult of fragmentation. The poetry of Ossian, she memorably argues, satisfied its readers by keeping them hungry, and by resisting eighteenth-century historiography in ways which were to be crucial to Scottish and American literatures in the future. Manning traces two key afterlives of Ossianic 'concerns and literary strategies': in the career of the prematurely venerable Henry Mackenzie, who chaired the Committee of the Highland Society that produced, in 1805, a report on the authenticity of Ossian, and in whose novels and autobiographical writings the ghosted script of Ossian survives; and in the life and work of Thomas Jefferson. Sometimes Manning's additions to the growing scholarship on fragments, such as her alignment of failed utterance with modern psychoanalytic work on trauma, place additional weight on her points of origin, the Act of Union and the epistemology of Hume; but this chapter contains compelling readings of familiar and less familiar texts, and is especially interesting on Burns's 'ghosted' work for James Johnson's and George Thomson's collections of Scottish songs. Manning here carries forward (though back in time) the interest in spectres which dominates chapter 5 of her earlier study The Puritan-Provincial Vision: Scottish and American Literature in the Nineteenth Century (1990). Ossian himself is projected into the consciousness of Jefferson, assisted by Hugh Blair's association between the language of Ossian's protagonists and that of the Amerindian peoples. The 'ghosted' or 'impersonated' 'Logan's speech' in Notes on the State of Virginia is both lament and translation, like Ossian's 'a voice articulating its own extinction from within the very discursive framework which was responsible for that disappearance' (184). It establishes the ground for Jefferson's more lastingly influential 'impersonation' of the 'American mind' in the Declaration of Independence, and for the terror of fragmentation that haunts Jefferson's 'proclamation of possibility' (194).

The fifth chapter, 'Gathering the Nation', returns to the geographies and boundaries of the second. It explores the ways in which nationhood 'could be assembled (rather like a Humean account of the mind) from catalogues of enumerated items' (197). Manning's points of reference are the 'aggretative taxonomy' of Jefferson's Notes on the State of Virginia (and the personality of that 'representative man' himself), his correspondent Hector St John de Crèvecoeur's Letters from an American Farmer, Margaret Fuller's Summer on the Lakes, Whitman's Leaves of Grass (demonstrably Ossianic in style - so are Blake's Prophetic Books, of course), and Poe's Eureka. Classification, tabulation, surveys, catalogues, computations and lists - as well as Jefferson's Amerindian vocabularies - share a paratactic syntax characteristic of Manning's fragmented but aggregative America. Largely because of Jefferson's passion for associative rather than incorporative forms, she posits, 'America had the idea of secession built into its formulations of union and identity' (223). Abraham Lincoln's rhetoric, in time, was to replace this with 'a masterpiece of subordinative prose' (225), the Gettysburg address.

Finally, Manning returns more explicitly to the linguistic and rhetorical concerns underpinning her study. Commentary on a range of grammatical and stylistic guides correcting the taint of 'Scotticisms' (listed in James Beattie's 'shadow-lexicon') leads to a study of the analogous debate on 'Americanisms'. The pressures on early American literature can be traced to matters of language and style, to the need for an 'independent' but also 'pure' diction. Emerson is the main focus of the first part of this chapter and the most engaged inheritor and combatant of what Manning calls 'Blair's double-bind' (259). Emerson's associative, paratactic Americanness prepares for Manning's interlinked readings of Emily Dickinson and William James, with their different approaches to continuity and disruption and their shared investigation of the nature of consciousness. 'As with Ossian's lament for lost national integrity, and Dickinson's truncated expression, the image of loss [in The Principles of Psychology] carries the implication of mutilation: the self has been sensibly violated by the severance' (283). In these ways the secessionist motif remains political, linguistic, psychological, philosophical, and literary from 1707 to 1890 and beyond.

As will be evident from the details I have given, this is a vivid and daring book. It relies on particulars but it also questions them, just as it questions our desire as critics to make them representative or connective. The methodology of Manning's study is closely and intriguingly bound up in the oppositions it identifies and analyses, making this, perhaps more than it explicitly states, an exploration of the apparent simplicity and lustre of the critical building-blocks of causation, contiguity, correspondence, analogy, and association. 'Join, or Die' warns the cartoon and the 'spectre of arbitrariness' conjured up towards the end of the Introduction, but Manning's trust lies also in the gaps, the resistance to becoming joined, and this produces some of the most exhilarating parts of her writing: 'And I too construct stories out of fragmentary observations in my own universe of the imagination' (31). Fragments of Union brilliantly combines scrupulous integration with a trust in fractures and glimpses, and it is a major contribution to interdisciplinary and transnational scholarship.